Joystick-Controlled Small EV Turning With Speed-Adaptive Motor Control
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Solution Overview
Problem
Existing small electric vehicles require users to hold the joystick at an intermediate position for slow speed turning, making it difficult to maintain an intended speed during navigation.
Innovation Solution
A small electric vehicle with left and right motors, rotation speed sensors, and a control unit that calculates target rotation speeds based on joystick operation and actual vehicle speed to adjust motor control for intuitive turning characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the speed is determined by the operation position of the joystick-type operation element, then the turning control is simplified, but the user cannot maintain the intended speed during turning
Solution Approach 1:
The control is segmented into two independent components: operation position determines target speed, while operation amount determines target angular velocity. This separation allows the user to maintain intended speed while achieving proper turning characteristics through the same intuitive joystick operation.
Solution Approach 2:
The control system changes parameters dynamically by calculating different target values (rotation speeds and angular velocity) based on the same operation input. The control unit computes target vehicle speed from operation position and target vehicle angular velocity from operation amount, then derives appropriate motor rotation speeds to maintain both speed and turning performance.
2Ease of operation
If the joystick is held at an intermediate position for slow speed turning, then turning is achieved, but the user cannot drive at the intended speed
Solution Approach 1:
By separating speed control (operation position) from turning control (operation amount), the system eliminates the need to hold the joystick at intermediate positions. Users can operate the joystick at full intended speed positions while the system independently manages turning through operation amount, thereby maintaining both turning capability and travel efficiency.
3Device complexity
If the turning characteristics are fixed, then the control system is simple, but the turning characteristics do not support different travel states
Solution Approach 1:
The control system dynamically adjusts turning characteristics based on actual vehicle speed. The control unit calculates target vehicle angular velocity by combining operation amount with detected actual speed, allowing turning characteristics to adapt to different travel states (slow/fast movement) while maintaining a relatively simple control architecture based on feedback control.
Solution Approach 2:
The system uses feedback from rotation speed sensors to detect actual motor speeds and vehicle movement state. This feedback is fed back to the control unit, which adjusts the target rotation speeds to achieve the desired turning characteristics appropriate for the current travel state, enabling adaptability without significantly increasing system complexity.
Data Source
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AI summary
Problem to be Solved: A small electric vehicle is provided that achieves turning characteristics supporting travel states, through intuitive operations on a joystick-type operation element. Solution: A small electric vehicle (1) includes: a vehicle body (2) that has a forward and backward direction, and a width direction; left and right driving wheels (4L and 4R) provided apart in the width direction of the vehicle body; free wheels (5) provided apart from the left and right driving wheels in the forward and backward direction; left and right motors (40L and 40R) connected so as to respectively transmit power to the left and right driving wheels; left and right rotation speed sensors (43) for detecting rotation speeds of the left and right motors; an operation unit (8) that includes a joystick-type operation element (83); and a control unit (10) that controls the left and right motors according to an amount of operation on the operation element, wherein the control unit is configured to calculate target rotation speeds of the left and right motors, based on a target vehicle speed (v) provided by an operation position of the operation element, and on a target vehicle angular velocity (ω) provided by the operation position of the operation element and by the actual speed of the vehicle, and control the left and right motors such that actual rotation speeds of the left and right motors follow the respective target rotation speeds.